nothing special; no big deal; doesn't matter
An emphatic, dismissive phrase used to brush off something as unimportant or not worth worrying about. Often used in response to a concern or boast.
"Are you okay? Doesn't it hurt?" "It's nothing, this much is fine."
彼は難しい試験もなんのその、満点を取った。
He aced the difficult exam as if it were nothing.
Usually written in kana; the kanji forms 何のその and 何の其の are rare and may be encountered in older texts.
Kanji form using 何; rarely used in modern writing.
Kanji form using 其の; very rare and archaic-looking.
From 何 (なん, 'what') + の (possessive particle) + 其の (その, 'that'). Literally 'what of that', used rhetorically to dismiss something as insignificant.